1. Field of the Invention
The present invention relates to a printing system including, for example, a preview function of displaying a print image to a user before execution of print processing.
2. Description of the Related Art
In a printing system using a computer provided with Windows (registered trademark) of Microsoft Corporation as an operating system (OS), print data generated by, for example, an application program is stored in a spool file in a data format standard for the OS.
The OS calls up a printer driver for printing the print data. Then, the printer driver reads the print data stored in the spool file, causes an image generation processing unit to generate a print image, and then converts it to a print command interpretable by a printer. The print command is transmitted to the printer. The printer interprets the print command and generates an image onto a recording medium, thereby performing print processing.
In this printing system, generally, a preview function is realized in the following manner. The printer driver activates a previewer, which functions to display the print image, when the print processing starts. Then, the image generation processing unit generates a print image for use in a preview, and the previewer displays this print image for the preview. Regarding this preview function, there is a technique of speeding up a preview display by starting with a display of a page for which image generation has been completed (Japanese Patent Application Laid-Open No. 2003-177905).
On the other hand, in recent years, there has appeared a printing system using the Extensible Markup Language Paper Specification (XPS) format as a data format stored in the spool file, instead of the Enhanced Meta File (EMF) format employed by the conventional technique. This printing system also employs an XPS printer driver that supports XPS documents as a printer driver.
The XPS format is an open standard electronic document format developed by Microsoft Corporation, and a display unit therefor is provided by the operating system (OS). According to the conventional technique, a print preview is displayed by conversion of print data into an image. However, the XPS printer driver can display a preview of an XPS document set as print data without converting it into an image by utilizing the display unit provided by the OS, while the conventional technique displays a preview by converting print data into an image.
When the XPS printer driver uses an XPS document set as print data for a preview without converting it, the XPS printer driver outputs preview data from the print data that is being processed to be printed. However, among filters (which will be described below) constituting the XPS printer driver, some of them employ an interface configured to receive an XPS document as parts into which the XPS document is divided.
If such an interface is used for print processing, data is processed in the form of individual parts constituting the XPS document and does not take a form of an XPS document, so that an XPS document for a preview should be constructed from the parts. All of the parts constituting the XPS document are required for construction of the preview XPS document corresponding to the print data from the parts.
However, for example, if the document includes a large number of pages, it takes long time until the filter can acquire all of the parts. Accordingly, it takes long time to generate a preview document (in the present invention, this will be also referred to as a “main display document”), thereby delaying realization of a preview display by the previewer.